Have you tested the sockets themselves?
Even if they test hot, they cand still get worn out to where they don.T make good contact with the bulb?
Do you have 1157 or 3157 bulba? Reason being the 1157 more prone to fail in regards to not making goood contact with the bulb. Reason being that the bottom plate has a spring behind it that can get weak over time and the contacts themselves can wear down.
The newer 3157, push in straight style, can stiil have the same issues, but less likley.
So, if the sockets are hot when you test them, they might still need replacement. If there is corrosion, you can try WD-40 and let it soak over night and then clean it out. Also, the eraser end of a pencil is good to clean off contacts even if they do not appear corroded as there is a type of corrosion, I forget what it is called, that is hard to see but will create resistance and the eraser will get rid of it.
One last thought, if you happen to be using an LED as an upgrade, sometimes they will have issues and end up being dimmer or not work because a diode does not work well with high amp changes. They usually need a box that handles this problem. They will not dim, blink or get brighter without it.
I hope this helps.
Let me know if you need anything else and I will keep an eye on this post and respond ASAP.
Sunday, February 6th, 2011 AT 6:46 PM